User equipment (UE), also known as mobile stations, wireless terminals and/or mobile terminals are enabled to communicate wirelessly in a wireless communication system, sometimes also referred to as a cellular radio system. The communication may be made e.g. between two user equipment units, between a user equipment and a regular telephone and/or between a user equipment and a server via a Radio Access Network (RAN) and possibly one or more core networks.
The user equipment units may further be referred to as mobile telephones, cellular telephones, laptops with wireless capability. The user equipment units in the present context may be, for example, portable, pocket-storable, hand-held, computer-comprised, or vehicle-mounted mobile devices, enabled to communicate voice and/or data, via the radio access network, with another entity, such as another user equipment or a server.
The wireless communication system covers a geographical area which is divided into cell areas, with each cell area being served by a network node, or base station e.g. a Radio Base Station (RBS), which in some networks may be referred to as “eNB”, “eNodeB”, “NodeB” or “B node”, depending on the technology and terminology used. The network nodes may be of different classes such as e.g. macro eNodeB, home eNodeB or pico base station, based on transmission power and thereby also cell size. A cell is the geographical area where radio coverage is provided by the network node/base station at a base station site. One base station, situated on the base station site, may serve one or several cells. The network nodes communicate over the air interface operating on radio frequencies with the user equipment units within range of the respective network node.
In some radio access networks, several network nodes may be connected, e.g. by landlines or microwave, to a Radio Network Controller (RNC) e.g. in Universal Mobile Telecommunications System (UMTS). The RNC, also sometimes termed a Base Station Controller (BSC) e.g. in GSM, may supervise and coordinate various activities of the plural network nodes connected thereto. GSM is an abbreviation for Global System for Mobile Communications (originally: Groupe Spécial Mobile).
In 3rd Generation Partnership Project (3GPP) Long Term Evolution (LTE), network nodes, or base stations, which may be referred to as eNodeBs or even eNBs, may be connected to one or more core networks.
UMTS is a third generation mobile communication system, which evolved from the GSM, and is intended to provide improved mobile communication services based on Wideband Code Division Multiple Access (WCDMA) access technology. UMTS Terrestrial Radio Access Network (UTRAN) is essentially a radio access network using wideband code division multiple access for user equipment units. The 3GPP has undertaken to evolve further the UTRAN and GSM based radio access network technologies.
The 3GPP is responsible for the standardization of e.g. GSM, UMTS and LTE. LTE is a technology for realizing high-speed packet-based communication that may reach high data rates both in the downlink and in the uplink, and is thought of as a next generation mobile communication system relative UMTS.
In the present context, the expressions downlink, downstream link or forward link may be used for the transmission path from the network node to the user equipment. The expression uplink, upstream link or reverse link may be used for the transmission path in the opposite direction i.e. from the user equipment to the network node.
The load of a typical base station varies over time. Hence there is need for a high capacity during busy hours while the demand may be significantly lower during other periods. There may also be significant change of load in shorter time spans i.e. from one minute to another. However, some of the components comprised in the base station may utilize a significant amount of energy, even if there is little traffic load. A possible concept of reducing the energy consumption of the base station may be to shut down the base station when it is not used, or shut down parts of the base station when the traffic load is low. However, with known prior art base stations, it is not possible, or at least not convenient to easily shut down parts of a base station to save power and at the same time supply the user equipment with the same accessibility, i.e. maintained coverage and functions but reduced capacity in number of user equipment units.
Energy efficient processing is becoming more and more important in cellular communication systems. One trend is to centralise base band processing to large nodes in order to reduce in particular Operating Expenditures (OPEX). For example, in order to reduce the number of sites and thus removing site acquisition and labour work that is a substantial high capital investment cost in the deployment. On the operational expenditure side maintenance, energy and transmission related costs may be at least somewhat reduced and saved.
Another trend in the industry is to go towards a higher degree of integration. Traditionally base band processing has been closely connected to the antenna sites such as main remote type eNB with short distance between the main unit and the radio unit.
Current implementations of base stations are built in such a way that no trunking effects may be achieved. Base stations may only be hard allocated to a specific site that handles a limited number of cells. No advantage may thus be achieved by reallocation of hardware resources when traffic demands are moving from one area to another area. Load balancing may thus only be achieved for a limited amount of hardware resources. In a centralised radio access network where base band resources are located at a site serving a large number of radio units it is still not possible to pool all resources without some load balancing technology.
There may be a general desire to save energy consumption in a base station. There may be another general desire to simplify service, management and software update of base stations. Also, there may be a desire to reduce hardware utilisation and costs associated therewith.